Robust label-free microRNA detection using one million ISFET array

Abstract

Detection of nucleic acid molecules is one of the most pervasive assays in biology, medicine, and agriculture applications. Currently, most comely used DNA/RNA detection platforms use fluorescence labeling and require lab-scale setting for performing the assay. There is a need for developing less expensive, label-free, and rapid detection of biomolecules with minimal utilization of resources. Use of electrical approaches for detection of biomolecules by utilizing their inherent charge is a promising direction for biosensing assays. Here, we report a 1024 × 1024 array of Ion Sensitive Field Effect Transistors (ISFET) as label free sensors for detection of nucleic acid molecules. Using PNA probe functionalized on these ISFET array, we robustly detected miRNA Let-7b by measuring changes in drain current after hybridization of target molecules with concentration as low as 1 nM. We demonstrate that mismatched or non-complementary target molecules resulted in statistically smaller changes. Most importantly, the high-density sensor array shows unprecedented reliability and robustness with P values <0.0001 for all experiments. Practical implementation of this platform could have a wide range of applications in high-throughput nucleic acid genotyping, detection of amplified pathogenic nucleic acid, detection of cell-free DNA, and electrical readouts for current hybridization-based DNA biomolecular assays.

Notes

Acknowledgements

We thank the staff at the Micro and Nanotechnology Laboratory at UIUC for facilitating the chip fabrication. The work was funded by NSF grant 1534126 and the University of Illinois at Urbana-Champaign.

Author contributions

A.G., Y.W. and R.B conceived the idea and designed the study. A.G. and Y.W., designed and performed the experiments. J.H. assisted with the experiments and provided intellectual inputs. M.H., A.G., Y.W. and R.B wrote and edited the manuscript.